JP2016044206A - Oil-based ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based composition which is excellent in printing quality, ejection stability, intermittent printing stability, fixability, storage stability or the like.SOLUTION: There is provided the oil-based composition containing at least a pigment, a polymer dispersant, a fixing resin and an organic solvent. The organic solvent contains at least polyoxyethylene glycol dialkyl ether represented by the following formula (1) and cyclic ester in an amount of less than 50 mass% in total. R-(OCH)-OR... the formula (1) (In the formula, Rand Rare each 1-3 alkyl group and may be the same or different, and n is an integer of 2 to 4).SELECTED DRAWING: None

Description

  The present invention relates to an oil-based ink composition.

  For the purpose of improving the ink-jet suitability of oil-based inks, research and development have been conducted on the types of organic solvents contained in the inks, their combinations and addition amounts, and many proposals have been made.

  For example, WO2004 / 007626 (Patent Document 1) contains at least 50% by weight of a mixed solvent containing 0.02 to 4 parts by weight of a lactone solvent with respect to 1 part by weight of polyoxyethylene glycol dialkyl ether. Oil based inks are disclosed. According to this document, the oil-based ink is suitable for printing on a polyvinyl chloride substrate, and is excellent in printing quality, printing stability, printing drying property, and ink storage stability.

  JP-A-2005-200469 (Patent Document 2) includes a glycol acetate compound and a cyclic ester, and the content of the cyclic ester is 1 to 60 parts by mass per 100 parts by mass of the glycol acetate compound. Certain oil-based inks are disclosed. According to this document, the oil-based ink is said to be excellent in ink ejection stability, fixability to a polyvinyl chloride film, and drying properties.

  JP-A-2011-052046 (Patent Document 3) discloses that 60% by mass or more of diethylene glycol diethyl ether, 24 to 37% by mass of γ-butyrolactone and / or tetraethylene glycol dimethyl ether, and more than 1% by mass. Metal pigment inks are disclosed that contain a high amount of less than 5% by weight of tetraethylene glycol monobutyl ether. According to this document, the metal pigment ink is said to be excellent in ejection stability and antifoaming property.

  WO2002 / 055619 (Patent Document 4) includes a mixture of a diethylene glycol compound that is liquid at normal temperature and pressure and a dipropylene glycol compound that is liquid at normal temperature and pressure, and the diethylene glycol compound and the dipropylene glycol compound An oil-based ink having a weight mixing ratio of 20:80 to 80:20 is disclosed. According to this document, the oil-based ink is said to be excellent in ejection stability, fixability to a vinyl chloride film, and storage stability.

WO2004 / 007626 Publication Japanese Unexamined Patent Publication No. 2005-200469 JP 2011-052046 A WO2002 / 055619 Publication

  The inventors of the present invention have recently made the specific range of the type and content of the organic solvent contained in the oil-based ink, thereby improving the printing quality, ejection stability, intermittent printing stability, fixing property, storage stability, etc. The inventor has obtained knowledge that an oil-based pigment ink composition excellent in inkjet suitability can be obtained. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide an oil-based pigment ink composition excellent in printing quality, ejection stability, intermittent printing stability, fixing property, storage stability, and the like.

And the oil-based ink composition according to the present invention comprises:
An oil-based ink composition comprising at least a pigment, a polymer dispersant, a fixing resin, and an organic solvent,
The organic solvent contains at least a polyoxyethylene glycol dialkyl ether represented by the following formula (1) and a cyclic ester in a total amount of less than 50% by mass.
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4).

Organic Solvent The oil-based ink composition according to the present invention has an organic solvent of the following formula (1) having a total amount of less than 50% by mass:
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4).
And at least both a polyoxyethylene glycol dialkyl ether and a cyclic ester. Thereby, the oil-based ink composition by this invention is excellent in discharge stability, intermittent printing stability, or the permeability | transmittance with respect to plastic base materials, such as a polyvinyl chloride.

Polyoxyethylene glycol dialkyl ether represented by the formula (1) The oil-based ink composition according to the present invention has the following formula (1) as an organic solvent:
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4).
The polyoxyethylene glycol dialkyl ether shown by these is included. Thereby, it is excellent in intermittent printing stability and permeability to plastic substrates such as polyvinyl chloride. The polyoxyethylene glycol dialkyl ether represented by the formula (1) has a high boiling point and a low vapor pressure, and is excellent in working environment or safety. And content of polyoxyethylene glycol dialkyl ether shown by Formula (1) is less than 50 mass% with respect to the whole quantity of an ink composition by the total amount with the cyclic ester mentioned later. The content of the polyoxyethylene glycol dialkyl ether represented by the formula (1) is preferably 36 to 47% by mass and more preferably 36 to 41% by mass with respect to the total amount of the ink composition.

  In the present invention, specific examples of the polyoxyethylene glycol dialkyl ether represented by the formula (1) include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n or iso-propyl ether, diethylene glycol ethyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol dimethyl ether, Ethylene glycol diethyl ether, triethylene glycol ethyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol di-n or iso-propyl ether, and tetraethylene glycol ethyl methyl ether, and two or more of these Combinations are mentioned.

  According to a preferred embodiment of the present invention, the polyoxyethylene glycol dialkyl ether represented by the formula (1) is diethylene glycol diethyl ether and / or tetraethylene glycol dimethyl ether. In particular, those containing both diethylene glycol diethyl ether and tetraethylene glycol dimethyl ether are preferable. The content of diethylene glycol diethyl ether is preferably 17 to 28% by mass with respect to the total amount of the ink composition. Further, the content of tetraethylene glycol dimethyl ether is preferably 12 to 18% by mass with respect to the total amount of the ink composition. The oil-based ink composition according to the present invention contains these polyoxyethylene glycol dialkyl ethers in the above ranges, whereby the intermittent printing stability is good.

Cyclic ester The oil-based ink composition according to the present invention contains a cyclic ester as an organic solvent. Thereby, the permeability with respect to plastic base materials, such as a polyvinyl chloride, improves. The content of the cyclic ester is less than 50% by mass with respect to the total amount of the ink composition as a total amount with the polyoxyethylene glycol dialkyl ether represented by the above-described formula (1). Thereby, it becomes possible to reduce or suppress the attack property to the structural member of a head. Moreover, it becomes possible to improve discharge stability, and the adaptability to continuous printing over a long time is improved. According to a preferred embodiment of the present invention, the content of the cyclic ester is 7 to 18% by mass with respect to the total amount of the ink composition.

（式中、Ｒ^４１およびＲ^４２は各々水素原子または炭素数１〜７のアルキル基もしくはアルケニル基であり、同一であっても異なっていてもよく、ｍは１〜３の整数である。）
で示されるラクトン系化合物が挙げられる。 In the present invention, as a specific example of the cyclic ester, the following formula (4):

(In the formula, R ⁴¹ and R ⁴² are each a hydrogen atom, an alkyl group or an alkenyl group having 1 to 7 carbon atoms, which may be the same or different, and m is an integer of 1 to 3).
The lactone type compound shown by these is mentioned.

  Examples of the lactone compound represented by the above formula (4) include γ-lactone such as γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprolactone, γ-laurolactone, δ-valerolactone, δ-lactone such as δ-hexalactone, and ε-lactone such as ε-caprolactone. Among these, one or more lactone compounds selected from the group consisting of γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone are preferable.

Glycol Acetate Compound According to a preferred embodiment of the present invention, the oil-based ink composition according to the present invention contains, as an organic solvent, the following formula (2):
R ²¹ — (O—CH ₂ —CHR ²² ) n-OCOCH ₃ Formula (2)
(In the formula, R ²¹ is an alkyl group having 1 to 4 carbon atoms, R ²² is a hydrogen atom or a methyl group, and n is an integer of 1 to 3).
The glycol acetate type compound shown by these is further included. Thereby, the permeability with respect to plastic base materials, such as a polyvinyl chloride, and the dispersion stability of a pigment improve. Further, there is no precipitation of solid content in the ink on the nozzle end face, no increase in the viscosity of the ink due to ink concentration in the nozzle, and excellent ink ejection stability and intermittent printing stability from the head nozzle. The addition amount of the glycol acetate compound represented by the formula (2) is preferably 25 to 55% by mass with respect to the total amount of the ink composition. Moreover, it is more preferable that it is 37-52 mass%.

  In the present invention, specific examples of the glycol acetate compound represented by the formula (2) include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether. Acetate, propylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol monobutyl ether acetate, and dipropylene glycol monomethyl Such as chromatography ether acetate. Among these, ethylene glycol monobutyl ether acetate is preferable. Moreover, it is preferable that content of the glycol acetate type compound shown by Formula (2) is 37-55 mass% with respect to the whole quantity of an ink composition.

Tetraethylene glycol alkyl ether According to a preferred embodiment of the present invention, the oil-based ink composition according to the present invention contains, as an organic solvent, the following formula (3):
R ³¹ — (OC ₂ H ₄ ) ₄ —OH Formula (3)
(In the formula, R ³¹ is an alkyl group having 1 to 4 carbon atoms.)
The tetraethylene glycol alkyl ether shown by these is further included. Thereby, it is possible to further improve the permeability to a plastic substrate such as polyvinyl chloride, the ejection stability, the intermittent printing stability or the storage stability, or these two or more functions and effects. The content of the tetraethylene glycol alkyl ether represented by the formula (3) is preferably 1 to 5% by mass with respect to the total amount of the ink composition.

  In the present invention, specific examples of the tetraethylene glycol alkyl ether represented by the formula (3) include tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monopropyl ether, and tetraethylene glycol monobutyl ether. . Among these, tetraethylene glycol monobutyl ether is preferable. Further, the content of the tetraethylene glycol alkyl ether represented by the formula (3) is preferably 1 to 5% by mass with respect to the total amount of the ink composition.

Other Solvents The oil-based ink composition according to the present invention can contain any solvent that can disperse the pigment without particular limitation in addition to the organic solvent described above. As such a solvent, for example, alcohol solvents, ester solvents, ketone solvents, glycol ether solvents, aliphatic solvents, alicyclic solvents, aromatic solvents, amine solvents, water and the like are preferable. Can be used. These solvents can also be used in combination of two or more.

  Specific examples of the alcohol solvent include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, 3-methoxy-3-methyl-1-butanol and the like. According to a preferred embodiment of the present invention, it is preferable to use a high-boiling alcohol solvent as the alcohol solvent from the viewpoint that a change in concentration accompanying evaporation of the solvent during surface treatment can be kept low. As the high-boiling alcohol solvent, 3-methoxy-3-methyl-1-butanol (MMB) can be preferably used.

  Specific examples of the ester solvent include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, dimethyl carbonate and the like.

  Specific examples of the ketone solvent include acetone, isophorone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, methyl isobutyl ketone benzene, diisobutyl ketone, diacetone alcohol, and the like. Among these, methyl isobutyl ketone can be mentioned from the viewpoint of safety.

  Specific examples of the glycol ether solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, other than polyoxyethylene glycol dialkyl ether represented by formula (1) and tetraethylene glycol alkyl ether represented by formula (3), Examples include ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether.

  Specific examples of the aliphatic solvent include n-heptane, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane and the like. Among these, ethylcyclohexane can be mentioned from the viewpoint of low volatility and easy handling.

  Specific examples of the aromatic solvent include toluene, xylene, tetralin and the like. Examples of other solvents include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform, amides such as dimethylformamide, and ethers such as tetrahydrofuran, ethyl ether, and dioxane.

  Specific examples of the amine solvent include monoethanolamine, diethanolamine, and triethanolamine. The amine solvent has an effect of improving the dispersion stability of the pigment, particularly in an oil-based ink in which the pigment is dispersed in an acetate solvent. The content of the amine solvent is preferably 0.3 to 3% by mass with respect to the total amount of the ink composition. Further, it is more preferably around 1% by mass.

Fixing Resin According to a preferred embodiment of the present invention, the oil-based ink composition according to the present invention further comprises a fixing resin. Thereby, the viscosity of the ink composition can be adjusted. As a result, the ejection stability or storage stability of the ink composition is improved. Moreover, the fixability of the pigment to the printing medium can be improved. As such a fixing resin, a known resin capable of forming a film can be used. For example, natural vegetable oil, natural organic resin, semi-synthetic organic resin, synthetic organic resin, or the like can be used. The fixing resin may be either a thermoplastic resin or a thermosetting resin. The fixing resin may be selected in accordance with required performance such as adhesion to a printing medium and the type of solvent contained in the oil-based ink. The content of the fixing resin is preferably 0.1 to 5% by mass with respect to the total amount of the ink composition in consideration of the dispersion stability of the pigment.

  Examples of fixing resins include linseed oil, soybean oil, dehydrated castor oil and semi-dry oil, alcoholic varnish, rosin, nitrocellulose, ethyl cellulose, cellulose acetate, cellulose butyrate, cellulose acetate butyrate (CAB), cellulose acetate Propionate (CAP), benzyl cellulose, novolak type or resol type phenol resin, urea resin, alkyd resin, amino resin, amino alkyd resin, acrylic resin, vinyl chloride resin, silicone resin, acrylic urethane resin, acrylic silicone resin, Modified thermoplastic or thermosetting fluororesin, epoxy resin, polyurethane resin, graft modified polyurethane resin, polyester resin, graft modified polyester resin, melamine resin, polyvinylidene chloride resin, polycarbonate Resin, epoxy resin, cashew resin, cinnamic acid resin, polythiol resin, polyolefin resin, chlorinated polyolefin resin, acid-modified polyolefin resin graft-modified with α, β-unsaturated carboxylic acid or its anhydride, acid-modified chlorine Examples thereof include graft-modified polyolefin resins graft-modified with reactive monomers typified by chlorinated polyolefin resins, acrylic monomers and the like, graft-modified chlorinated polyolefin resins, copolymers and aqueous products of the above resins, and mixtures thereof. Among these, one or two selected from the group consisting of cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP), chlorinated polyolefin resin, acid-modified chlorinated polyolefin resin, and graft-modified chlorinated polyolefin resin More than species are preferred.

Pigment The oil-based ink composition according to the present invention contains a pigment. Thereby, weather resistance, such as water resistance of a printed matter, light resistance, and gas resistance, is excellent. Examples of the pigment include known inorganic pigments and organic pigments that are usually used in oil-based ink compositions. Specifically, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, titanium oxide, viridian, titanium cobalt green, ultramarine blue, Prussian blue, cobalt blue, diketopyrrolopyrrole, Anthraquinone, benzimidazolone, anthrapyrimidine, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, selenium pigment, perylene pigment, perinone pigment, thioindigo pigment, quinophthalone A pigment, a metal complex pigment, or the like can be used. These pigments may be used alone or in combination of two or more. Moreover, it is preferable that content of a pigment is 0.5-15 mass% with respect to the whole quantity of an ink composition.

  The oil-based ink composition according to the present invention may contain a metal pigment as a pigment. Specific examples of metal pigments include aluminum pigments. The shape, size and the like of the aluminum pigment are not particularly limited, but the shape is flaky, the average particle diameter (D50: cumulative weight 50% particle diameter) is 1 to 20 μm, and the thickness is 5 to 50 nm. The aspect ratio (average particle diameter / thickness) is preferably 20 to 4,000. The shape of the aluminum flakes is preferably a flat shape, and may be a coin shape (a shape having a smooth surface and rounded surface).

  As a production method for producing aluminum flakes, for example, a method of pulverizing or grinding an atomized powder (powder obtained by the atomization method) by a ball mill, a method of peeling an aluminum layer after producing an aluminum vapor-deposited film, and pulverizing it. Can be used. Moreover, it does not specifically limit about the purity (metal component) of aluminum flakes, Industrial pure aluminum and a well-known aluminum alloy can be used.

Polymer Dispersant The oil-based ink composition according to the present invention contains a polymer dispersant. The polymer dispersant can be used without particular limitation as long as it can stably disperse the pigment in the organic solvent described above, and has both a hydrophobic part and a hydrophilic part in its structure. Is preferred. This makes it possible for the hydrophobic part of the polymer dispersant to physically adsorb to the hydrophobic surface of the pigment particles, and to adapt to the hydrophobic part of the organic solvent, so that the pigment is stable in the solvent. Can be dispersed. Such polymer dispersants include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polycarboxylic acids, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, and sulfur-containing polymers. Polymers, fluorine-containing polymers, epoxy resins and the like can be preferably used.

  More preferable polymer dispersants include hydroxyl group-containing carboxylic acid esters, salts of long chain polyaminoamides and high molecular weight acid esters, salts of high molecular weight polycarboxylic acids, salts of long chain polyaminoamides and polar acid esters, Saturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalenesulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonylphenyl ether, polyester Examples include polyamine and stearylamine acetate.

  Specific examples of the polymer dispersant include Dispersic 130, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 170, Dispersic 171, Dispersic 174, Dispersic 180, Dispersic 182 manufactured by BYK Chemie. Dispersic 183, Dispersic 184, Dispersic 185, Dispersic 2000, Dispersic 2001, Dispersic 2020, Dispersic 2050, Dispersic 2070, Dispersic 2096, Dispersic 2150, Dispersic LPN21116, Dispersic LPN6919; EFKA46, EFKA47, EFKA48, EFKA49, EFKA4010, EFKA 055 (modified polyurethane), Fuka 452, Fuka LP4008, Fuka 4009, Fuka LP4010, Fuka LP4050, Fuka LP4055, Fuka 400, Fuka 401, Fuka 402, Fuka 403, Fuka 450, Fuka 451, Fuka 453 (modified polyacrylate), Efka 4540, Efka 4550, Efka LP4560, Efka 120, Efka 150, Efka 1501, Efka 1502, Efka 1503; Solsperse 3000 (hydrostearic acid type dispersant), Solsperse 5000 (phthalocyanine ammonium salt type dispersant) manufactured by Lubrizol Solsperse 9000, Solsperse 13240, Solsperse 13650, Solsperse 13940 (polyesteramine type), Solsperse 17000 Solsperse 18000 (fatty acid amine dispersant), Solsperse 11200, Solsperse 20000, Solsperse 21000, Solsperse 22000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000 (polyamide dispersant), Solsperse 32000, Solsperse 36000, Solsperse 37000, Solsperse 38000, Solsperse 41000, Solsperse 42000, Solsperse 43000, Solsperse 46000, Solsperse 54000, Solsperse 71000; DEMOL P, EP, POISE 520, 521, 530, homogenol L-18 (polycarboxylic acid type polymer surfactant) manufactured by Kao Corporation ), Ajinomoto Co., Ltd. Ajisper PB711, Ajispa -PB821, Ajisper PB822, Azisper PB814, Azisper PN411, Azisper PA111; Disparon KS-860, KS-873N4 (amine salt of high molecular polyester) manufactured by Enomoto Kasei Co., Ltd .; TAMN-15 (Polyalkylamine PO manufactured by Nikko Chemical Co., Ltd.) Or EO modified product); DISCOL 202, 206, OA-202, OA-600 (multi-chain polymer nonionic dispersant) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  As another specific example, there can be mentioned a polyamide-based dispersant having a comb structure having a plurality of nitrogen atoms in the main chain and a plurality of side chains amide-bonded via the nitrogen atoms. As the main chain, polyalkylimine can be preferably mentioned, and polyethyleneimine can be mentioned. Moreover, as a side chain, a polyester chain can be mentioned suitably and a poly (carbonyl- C3-C6-alkyleneoxy) chain can be mentioned more suitably. Specific examples of such a polyamide-based dispersant include 3 to 80 poly (carbonyl-C3-C6-C6) molecules per main chain composed of polyethyleneimine as disclosed in JP-A-5-177123. A compound having a structure in which an (alkyleneoxy) chain is bonded as a side chain by an amide bond. Since such a compound has high ionicity at the adsorption site with the surface of the aluminum pigment, it is considered that, for example, the binding reaction between the alkoxysilane compound and the surface of the aluminum pigment can be promoted. In such a bonding reaction, a silanol group generated by hydrolysis of an alkoxysilane compound is adsorbed on the surface of the aluminum pigment through a hydrogen bond with a hydroxyl group on the surface of the aluminum pigment, and further undergoes a dehydration condensation reaction. This is considered to be formed by forming a strong covalent bond with the surface of the aluminum pigment. Examples of the comb-shaped polyamide-based dispersant include Solsperse 11200 and Solsperse 28000 manufactured by Lubrizol.

Surfactant According to a preferred embodiment of the present invention, the oil-based ink composition according to the present invention further comprises a surfactant. As a result, the wettability of the ink composition to the printing medium is improved, and quick fixability can be obtained. As the surfactant, known anionic, cationic, amphoteric or nonionic surfactants can be used, and the surfactant is an acetylene glycol surfactant and / or a silicone surfactant. It is preferable. The content of the surfactant is preferably 0.1 to 3% by mass with respect to the total amount of the ink composition.

  Examples of the acetylene glycol surfactant include Surfynol 465 (trademark), Surfhinol 104 (trademark) (above, manufactured by Air Products and Chemicals, Inc.), Olfine STG (trademark), Olfine E1010 (trademark) (above, Nissin Chemical Co., Ltd.) can be preferably used.

  As the silicone surfactant, polyester-modified silicone or polyether-modified silicone is preferably used. Specific examples include BYK-347, BYK-348, BYK-UV3500, BYK-UV3570, BYK-UV3510, BYK-UV3530 (Bicchemy Japan Co., Ltd.).

Production Method According to another aspect of the present invention, there is provided a method for producing an oil-based ink composition according to the present invention, which comprises:
Pigment, dispersant, and polyoxyethylene glycol dialkyl ether represented by the following formula (1):
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4).
And / or a glycol acetate compound represented by the following formula (2):
R ²¹ — (O—CH ₂ —CHR ²² ) n-OCOCH ₃ Formula (2)
(In the formula, R ²¹ is an alkyl group having 1 to 4 carbon atoms, R ²² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3).
And at least mixing to obtain a pigment dispersion,
At least a step of mixing the obtained pigment dispersion and an organic solvent to obtain an oil-based ink composition,
The organic solvent contains at least a polyoxyethylene glycol dialkyl ether represented by the formula (1) and a cyclic ester in a total amount of less than 50% by mass.

  According to the method for producing an oil-based ink according to the present invention, a dispersion is prepared by previously dispersing a pigment in ethylene glycol monobutyl ether acetate and / or tetraethylene glycol dimethyl ether, and this dispersion is appropriately mixed with an organic solvent. Thus, stable ink can be produced efficiently. Moreover, it is preferable that the said organic solvent further contains the amine solvent mentioned above. Thereby, the dispersion stability of a pigment improves.

  In the present invention, the polyoxyethylene glycol dialkyl ether represented by the formula (1) is preferably tetraethylene glycol dimethyl ether, and the glycol acetate compound represented by the formula (2) is preferably ethylene glycol monobutyl ether acetate.

  In the present invention, the organic solvent preferably contains an amine solvent. Details of the amine solvent are as described above.

Applications The oil-based ink composition according to the present invention is used as a solvent-based ink used in various applications such as pens, sprays, letterpress printing, gravure printing, offset printing, screen printing and inkjet printing, paints, coating compositions, and toners. Can do. In particular, it can be used as an ink for inkjet printing applied to a plastic substrate such as polyvinyl chloride.

Printing Method According to another aspect of the present invention, there is provided an inkjet printing method characterized in that the oil-based ink composition according to the present invention is applied to a printing medium to form an image. Examples of the printing medium to which the oil-based ink composition according to the present invention is applied include, for example, ink-jet exclusive paper (matte paper, glossy paper, etc.), synthetic paper (eg, YUPO paper) composed mainly of resin, wallpaper, glass, and the like. Various materials such as a plastic film or sheet (including a surface-treated plastic film or sheet), a substrate coated with plastic or an ink receiving layer (resin), a metal, a printed wiring board, and the like can be used. Specific examples of the plastic film or sheet include a hard or soft polyvinyl chloride film or sheet. Specific examples of the polyvinyl chloride film or sheet include a vinyl chloride film or sheet with glue, tarpaulin and the like.

  The following examples further illustrate the present invention. In addition, this invention is not limited by these Examples.

  Each oil-based ink composition shown below as an example was prepared.

Preparation of cyan (C) ink Cyan (C) pigment dispersion C.I. I. 15 parts by weight of CI Pigment Blue 15: 3, and 1/5 parts by weight of a polyester polymer compound “Hinoact KF1-M” (manufactured by Takefu Fine Chemical Co., Ltd.) as a dispersant with respect to the pigment, ethylene glycol mono After adding to 82 parts by mass of butyl ether acetate and stirring at 3,000 rpm for 1 hour with a dissolver, it was predispersed in a bead mill filled with zirconia beads (2 mm). Next, the main dispersion was performed with a nanomill filled with zirconia beads (0.3 mm) to obtain a C pigment dispersion. The average particle diameter of the obtained pigment particles was 145 nm. The average particle diameter was measured using “Microtrac UPA150” manufactured by Nikkiso Co., Ltd.

C ink As a fixing resin, CAB (butylation rate: 35 to 39%, manufactured by Kanto Chemical Co., Inc.), the following organic solvent mixed solution, and BYK-UV3500 (manufactured by Big Chemie Japan Co., Ltd.) as a surfactant are mixed as appropriate. A solvent was obtained. Next, a C pigment dispersion was added to the ink solvent, and mixed and stirred with a magnetic stirrer at room temperature and normal pressure for 30 minutes to obtain C ink having the composition shown in Table 1. The viscosity of the obtained ink was 4.3 mPa · s (20 ° C.). The viscosity was measured using an “AMVn” viscometer manufactured by Anton Paar.
Organic solvent mixture γ-butyrolactone tetraethylene glycol dimethyl ether (TeEGdME)
Diethylene glycol diethyl ether (DEGdEE)
Tetraethylene glycol monobutyl ether (TeEGmBE)
Ethylene glycol monobutyl ether acetate (EGmBEA)

Preparation of magenta (M) ink Magenta (M) pigment dispersion C.I. I. An M pigment dispersion was obtained in the same manner as the C pigment dispersion, except that 13 parts by mass of Pigment Red 122 was used. The average particle diameter of the obtained pigment particles was 120 nm.

M ink M inks having the compositions shown in Table 1 were obtained in the same manner as the C ink preparation method except that the M pigment dispersion was used. The viscosity of the obtained ink was 4.2 mPa · s (20 ° C.).

Preparation of yellow (Y) ink Yellow (Y) pigment dispersion C.I. I. A Y pigment dispersion was obtained in the same manner as the C pigment dispersion, except that 17 parts by weight of Pigment Yellow 74 was used. The average particle diameter of the obtained pigment particles was 100 nm.

Y ink A Y ink having the composition shown in Table 1 was prepared in the same manner as the C ink preparation method except that a Y pigment dispersion was used and triethanolamine (TEA) was further added to the organic solvent mixture. Obtained. The viscosity of the obtained ink was 4.1 mPa · s (20 ° C.).

Preparation of black (K) ink Black (K) pigment dispersion Preparation of C pigment dispersion except that 15 parts by mass of carbon black "MA-8" (manufactured by Mitsubishi Chemical Corporation) was used as the black pigment. In the same manner as in the method, a K pigment dispersion was obtained. The average particle diameter of the obtained pigment particles was 90 nm.

K ink A K ink having the composition shown in Table 1 was obtained in the same manner as the C ink preparation method, except that the K pigment dispersion was used and the organic solvent mixture was further added with TEA. The viscosity of the obtained ink was 4.2 mPa · s (20 ° C.).

Preparation of light magenta (Lm) ink Super Clon 390S (manufactured by Nippon Paper Industries Co., Ltd., chlorinated polyolefin resin) and the above organic solvent mixture further added with TEA, and BYK-UV3570 as a surfactant (Bick Chemie Japan) was mixed as appropriate to obtain an ink solvent. Next, the M pigment dispersion was added to the ink solvent, and Lm inks having the compositions shown in Table 1 were obtained in the same manner as in the M ink preparation method. The viscosity of the obtained ink was 3.9 mPa · s (20 ° C.).

Preparation of Light Cyan (Lc) Ink Lc ink was obtained in the same manner as the Lm ink preparation method except that the C pigment dispersion was used. The viscosity of the obtained ink was 4.2 mPa · s (20 ° C.).

Preparation of white (W) ink White (W) pigment dispersion A W pigment dispersion was obtained in the same manner as the C pigment dispersion except that 50 parts by mass of titanium oxide was used as the white pigment. . The average particle diameter of the obtained pigment particles was 305 nm.

W ink W ink was obtained in the same manner as the Lm ink preparation method except that the W pigment dispersion was used (however, the organic solvent mixture did not contain TEA). The viscosity of the obtained ink was 8.3 mPa · s (20 ° C.).

Preparation of metallic ink Aluminum (Al) pigment dispersion As a raw material aluminum pigment, Metashen (registered trademark) 41-0410 (ethyl acetate slurry of 10% aluminum flakes, manufactured by BASF) was used. Next, ethyl acetate (boiling point 77 ° C.) contained in the raw material aluminum pigment was distilled off under reduced pressure to prepare an Al pigment dispersion liquid substituted with TeEGdME (boiling point 275 to 276 ° C.). Specifically, in a 1 L eggplant flask, 300 g of raw material aluminum pigment (solid content 30 g), 300 g of TeEGdME, and 1.5 g of “Solsperse 3000” (manufactured by Lubrizol) were added and mixed. While being heated to room temperature (room temperature to 30 ° C.), vacuum distillation was performed with an evaporator. The pressure was reduced with an aspirator, and the pressure was reduced to about 20 mmHg. As a result, ethyl acetate was distilled off to obtain TeEGdME slurry of aluminum flakes derived from MetaShen (registered trademark) 41-0410. Furthermore, after stirring at 3,000 rpm for 1 hour with a dissolver, it was predispersed in a bead mill filled with zirconia beads (2 mm). Subsequently, it was pulverized with a nanomill filled with zirconia beads (0.3 mm) to adjust the average particle size of the aluminum flakes to 1 nm.

Metallic ink A metallic ink was obtained in the same manner as the C ink preparation method, except that an Al pigment dispersion was used and TEA was further added to the organic solvent mixture. The viscosity of the obtained ink was 4.2 mPa · s (20 ° C.).

Evaluation test Each of the oil-based inks prepared as described above was subjected to a polyvinyl chloride film (VS-300i, manufactured by Roland DG, Inc., equipped with an ink circulation mechanism in the head of white ink and metallic ink). LLJET Glossy PVC Gray Paste A (manufactured by Sakurai Co., Ltd.) and the following various evaluations were performed.

An alphabet character print having a print quality of 10 points was carried out and evaluated visually according to the following criteria. The results are shown in Table 2.
Standard evaluation A: No occurrence of bleeding.
Evaluation B: There is some bleeding, but character discrimination is possible.
Evaluation C: Large blur occurs and character discrimination is impossible.

Discharge stability Continuous printing was performed at room temperature, and the presence or absence of ink discharge failure was evaluated according to the following criteria. The results are shown in Table 2.
Reference evaluation A: The occurrence of defective ink ejection was less than 10 times within a continuous test period of 72 hours.
Evaluation B: Within a continuous test period of 72 hours, dot missing and ink ejection failure occurred 10 times or more and less than 20 times.
Evaluation C: Occurrence of dot omission and ink ejection failure was 20 times or more within a continuous test period of 72 hours.

Intermittent printing stability Similar to the ejection stability test, after printing for 10 minutes, the printing operation was interrupted, the head was removed from the cap position of the home position, and left in a released state for a certain period of time. Thereafter, the printing operation was restarted, and whether or not an ink ejection defect occurred was evaluated according to the following criteria.
Standard evaluation A: No ink ejection failure after resumption even after being allowed to stand for 1 minute.
Evaluation B: Even after being allowed to stand for 30 seconds, no ink ejection failure after resumption occurred.
Evaluation C: When left for 30 seconds, ink ejection failure occurred after resumption.

Solid printing with a fixing printing duty of 100% was performed, and the printed matter was dried for 12 hours in an environment of 25 ° C. and 50% (relative humidity), and then the printed surface was rubbed strongly with a finger and evaluated according to the following criteria. The results are shown in Table 2.
Criteria A: No printing stains and no ink peeling.
Evaluation B: Print stains and ink peeling occurred slightly, but there was no problem in identifying characters.
Evaluation C: Both printing stains and ink peeling occurred.

50 g of the storage stability ink was collected and sealed in a glass sample bottle and allowed to stand at 60 ° C. for 1 week, and the viscosity and average particle diameter of the ink were measured. The storage stability was evaluated according to the following criteria. The results are shown in Table 2.
Standard evaluation S: The difference in viscosity and average particle size was less than 3% before and after standing.
Evaluation A: The difference between the viscosity and the average particle diameter was less than 5% before and after standing.
Evaluation B: The difference between the viscosity and the average particle diameter was less than 10% before and after standing.
Evaluation C: The difference between the viscosity and the average particle diameter was 10% or more before and after standing.

Claims (22)

An oil-based ink composition comprising at least a pigment, a polymer dispersant, a fixing resin, and an organic solvent,
An oil-based ink composition, wherein the organic solvent contains at least a polyoxyethylene glycol dialkyl ether represented by the following formula (1) and a cyclic ester in a total amount of less than 50% by mass.
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4). The oil-based ink composition according to claim 1, wherein the organic solvent further contains a glycol acetate compound represented by the following formula (2).
R ²¹ — (O—CH ₂ —CHR ²² ) n-OCOCH ₃ Formula (2)
(In the formula, R ²¹ is an alkyl group having 1 to 4 carbon atoms, R ²² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3). The oil-based ink composition according to claim 1 or 2, wherein the organic solvent further contains a tetraethylene glycol monoalkyl ether represented by the following formula (3).
R ³¹ — (OC ₂ H ₄ ) ₄ —OH Formula (3)
(In the formula, R ³¹ is an alkyl group having 1 to 4 carbon atoms.)   The oil-based ink composition according to any one of claims 1 to 3, wherein the ethylene glycol dialkyl ether represented by the formula (1) is diethylene glycol diethyl ether and / or tetraethylene glycol dimethyl ether.   The oil-based ink composition according to any one of claims 1 to 4, wherein the content of the ethylene glycol dialkyl ether represented by the formula (1) is 29 to 46% by mass. The oil-based ink composition according to any one of claims 1 to 5, wherein the cyclic ester is a compound represented by the following formula (4).

(In the formula, R ⁴¹ and R ⁴² are each a hydrogen atom, an alkyl group or an alkenyl group having 1 to 7 carbon atoms, which may be the same or different, and m is an integer of 1 to 3).   The oil-based ink composition according to claim 6, wherein the cyclic ester is one or more selected from the group consisting of γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone. .   The oil-based ink composition according to claim 6 or 7, wherein the content of the cyclic ester is 7 to 18% by mass.   The oil-based ink composition according to any one of claims 2 to 8, wherein the glycol acetate compound represented by the formula (2) is ethylene glycol monobutyl ether acetate.   The oil-based ink composition according to any one of claims 2 to 9, wherein the content of the glycol acetate compound represented by the formula (2) is 25 to 55 mass%.   The oil-based ink composition according to any one of claims 3 to 10, wherein the tetraethylene glycol monoalkyl ether represented by the following formula (3) is tetraethylene glycol monobutyl ether.   The oil-based ink composition according to any one of claims 3 to 11, wherein the content of the tetraethylene glycol monoalkyl ether represented by the following formula (3) is 1 to 5% by mass.   The oil-based ink composition according to any one of claims 1 to 12, wherein the organic solvent further contains an amine solvent.   The oil-based ink composition according to claim 13, wherein the amine solvent is one or more selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine.   The oil-based ink composition according to claim 13 or 14, wherein the content of the amine solvent is 0.3 to 3% by mass.   The fixing resin is one or more selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate, chlorinated polyolefin resin, acid-modified chlorinated polyolefin resin, and graft-modified chlorinated polyolefin resin. The oil-based ink composition according to any one of claims 1 to 15.   The oil-based ink composition according to any one of claims 1 to 16, further comprising a surfactant.   The oil-based ink composition according to claim 1, which is applied to a plastic film or sheet. A method for producing the oil-based ink composition according to any one of claims 1 to 18,
Pigment, dispersant, and polyoxyethylene glycol dialkyl ether represented by the following formula (1):
R ¹¹ — (OC ₂ H ₄ ) _n —OR ¹² formula (1)
(In the formula, R ¹¹ and R ¹² are each an alkyl group having 1 to 3 carbon atoms, which may be the same or different, and n is an integer of 2 to 4).
And / or a glycol acetate compound represented by the following formula (2):
R ²¹ — (O—CH ₂ —CHR ²² ) n-OCOCH ₃ Formula (2)
(In the formula, R ²¹ is an alkyl group having 1 to 4 carbon atoms, R ²² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3).
And at least mixing to obtain a pigment dispersion,
A production method comprising at least a step of mixing the obtained pigment dispersion and an organic solvent to obtain an oil-based ink composition.   The production according to claim 19, wherein the polyoxyethylene glycol dialkyl ether represented by the formula (1) is tetraethylene glycol dimethyl ether, and the glycol acetate compound represented by the formula (2) is ethylene glycol monobutyl ether acetate. Method.   The manufacturing method according to claim 19 or 20, wherein the organic solvent comprises an amine solvent.   An ink-jet printing method comprising applying the oil-based ink composition according to claim 1 to a plastic film or sheet to form an image.